There are the 'larger than life' characters like Superman, who defeat all foes in a seemingly never-ending supply of victories. And there are the heroes who are, in thier own many ways, more impressive. Characters like Indiana Jones, who gets captured, tortured and either shot or stabbed before he can even come close to beating the bad guys to the punch. People like the soldiers who fight our wars in the world; they don't march tirelessly towards the enemy, soaking up bullets like they're made of steel, but through tactics and determination, they are more heroic than any Superman.
That's because they have flaws, they're human, they aren't enhanced by the power of Earth's yellow sun. They can die, they can bleed, and they probably don't even think of themselves as heroes. Like the character in Amon Amarth's song, The Hero. He says that 'The blade I swing is black as night, black as my souless heart', but later, 'But there I was, on battleground - until I felt the jaws of death cut into my fles - defending old and weak. But I, did not retreat'.
It's such a dichotomy of good/evil, or perceptions thereof, that make the best heroes the best heroes. Batman uses brutal scare tactics, our soldiers are highly trained killing machines and one of the most popular sci-fi heroes, Malcolm Reynolds, shoots a lawman in cold blood in the first episode.
But when you think about it, Batman's fighting the Joker, the soldiers are fighting an unpredictable enemy, and the lawman was Alliance. So really - you have to think about every damn thing when you're coming up with a hero. Don't just go Superman. Make them flawed, give them a mean streak. They're more human that way, like the soldiers.